1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2003-2009 Erwin Coumans http://bulletphysics.org
4
5 This software is provided 'as-is', without any express or implied warranty.
6 In no event will the authors be held liable for any damages arising from the use of this software.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10
11 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
13 3. This notice may not be removed or altered from any source distribution.
14 */
15
16 #ifndef BT_HEIGHTFIELD_TERRAIN_SHAPE_H
17 #define BT_HEIGHTFIELD_TERRAIN_SHAPE_H
18
19 #include "btConcaveShape.h"
20
21 ///btHeightfieldTerrainShape simulates a 2D heightfield terrain
22 /**
23 The caller is responsible for maintaining the heightfield array; this
24 class does not make a copy.
25
26 The heightfield can be dynamic so long as the min/max height values
27 capture the extremes (heights must always be in that range).
28
29 The local origin of the heightfield is assumed to be the exact
30 center (as determined by width and length and height, with each
31 axis multiplied by the localScaling).
32
33 \b NOTE: be careful with coordinates. If you have a heightfield with a local
34 min height of -100m, and a max height of +500m, you may be tempted to place it
35 at the origin (0,0) and expect the heights in world coordinates to be
36 -100 to +500 meters.
37 Actually, the heights will be -300 to +300m, because bullet will re-center
38 the heightfield based on its AABB (which is determined by the min/max
39 heights). So keep in mind that once you create a btHeightfieldTerrainShape
40 object, the heights will be adjusted relative to the center of the AABB. This
41 is different to the behavior of many rendering engines, but is useful for
42 physics engines.
43
44 Most (but not all) rendering and heightfield libraries assume upAxis = 1
45 (that is, the y-axis is "up"). This class allows any of the 3 coordinates
46 to be "up". Make sure your choice of axis is consistent with your rendering
47 system.
48
49 The heightfield heights are determined from the data type used for the
50 heightfieldData array.
51
52 - PHY_UCHAR: height at a point is the uchar value at the
53 grid point, multipled by heightScale. uchar isn't recommended
54 because of its inability to deal with negative values, and
55 low resolution (8-bit).
56
57 - PHY_SHORT: height at a point is the short int value at that grid
58 point, multipled by heightScale.
59
60 - PHY_FLOAT: height at a point is the float value at that grid
61 point. heightScale is ignored when using the float heightfield
62 data type.
63
64 Whatever the caller specifies as minHeight and maxHeight will be honored.
65 The class will not inspect the heightfield to discover the actual minimum
66 or maximum heights. These values are used to determine the heightfield's
67 axis-aligned bounding box, multiplied by localScaling.
68
69 For usage and testing see the TerrainDemo.
70 */
ATTRIBUTE_ALIGNED16(class)71 ATTRIBUTE_ALIGNED16(class) btHeightfieldTerrainShape : public btConcaveShape
72 {
73 protected:
74 btVector3 m_localAabbMin;
75 btVector3 m_localAabbMax;
76 btVector3 m_localOrigin;
77
78 ///terrain data
79 int m_heightStickWidth;
80 int m_heightStickLength;
81 btScalar m_minHeight;
82 btScalar m_maxHeight;
83 btScalar m_width;
84 btScalar m_length;
85 btScalar m_heightScale;
86 union
87 {
88 const unsigned char* m_heightfieldDataUnsignedChar;
89 const short* m_heightfieldDataShort;
90 const btScalar* m_heightfieldDataFloat;
91 const void* m_heightfieldDataUnknown;
92 };
93
94 PHY_ScalarType m_heightDataType;
95 bool m_flipQuadEdges;
96 bool m_useDiamondSubdivision;
97 bool m_useZigzagSubdivision;
98
99 int m_upAxis;
100
101 btVector3 m_localScaling;
102
103 virtual btScalar getRawHeightFieldValue(int x,int y) const;
104 void quantizeWithClamp(int* out, const btVector3& point,int isMax) const;
105 void getVertex(int x,int y,btVector3& vertex) const;
106
107
108
109 /// protected initialization
110 /**
111 Handles the work of constructors so that public constructors can be
112 backwards-compatible without a lot of copy/paste.
113 */
114 void initialize(int heightStickWidth, int heightStickLength,
115 const void* heightfieldData, btScalar heightScale,
116 btScalar minHeight, btScalar maxHeight, int upAxis,
117 PHY_ScalarType heightDataType, bool flipQuadEdges);
118
119 public:
120
121 BT_DECLARE_ALIGNED_ALLOCATOR();
122
123 /// preferred constructor
124 /**
125 This constructor supports a range of heightfield
126 data types, and allows for a non-zero minimum height value.
127 heightScale is needed for any integer-based heightfield data types.
128 */
129 btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,
130 const void* heightfieldData, btScalar heightScale,
131 btScalar minHeight, btScalar maxHeight,
132 int upAxis, PHY_ScalarType heightDataType,
133 bool flipQuadEdges);
134
135 /// legacy constructor
136 /**
137 The legacy constructor assumes the heightfield has a minimum height
138 of zero. Only unsigned char or floats are supported. For legacy
139 compatibility reasons, heightScale is calculated as maxHeight / 65535
140 (and is only used when useFloatData = false).
141 */
142 btHeightfieldTerrainShape(int heightStickWidth,int heightStickLength,const void* heightfieldData, btScalar maxHeight,int upAxis,bool useFloatData,bool flipQuadEdges);
143
144 virtual ~btHeightfieldTerrainShape();
145
146
147 void setUseDiamondSubdivision(bool useDiamondSubdivision=true) { m_useDiamondSubdivision = useDiamondSubdivision;}
148
149 ///could help compatibility with Ogre heightfields. See https://code.google.com/p/bullet/issues/detail?id=625
150 void setUseZigzagSubdivision(bool useZigzagSubdivision=true) { m_useZigzagSubdivision = useZigzagSubdivision;}
151
152 virtual void getAabb(const btTransform& t,btVector3& aabbMin,btVector3& aabbMax) const;
153
154 virtual void processAllTriangles(btTriangleCallback* callback,const btVector3& aabbMin,const btVector3& aabbMax) const;
155
156 virtual void calculateLocalInertia(btScalar mass,btVector3& inertia) const;
157
158 virtual void setLocalScaling(const btVector3& scaling);
159
160 virtual const btVector3& getLocalScaling() const;
161
162 //debugging
163 virtual const char* getName()const {return "HEIGHTFIELD";}
164
165 };
166
167 #endif //BT_HEIGHTFIELD_TERRAIN_SHAPE_H
168